Pressure sensors and switches may utilize different forms of diaphragms for their sensing operations. The diaphragms are often configured in flat-bed shape, wobble-shape and plate-like shape. Such diaphragms can be arranged in micro switches or pressure sensors. Currently, wobblefram designed diaphragms are generally utilized in micro switch devices due to their high operating performances. A wobblefram is essentially a flexible circular diaphragm with a fixed edge and a solid center region, to which a lever can be attached. The lever in the solid center region can be utilized to actuate the internal switching mechanism of the micro switches. The wobblefram also acts as a seal to allow free movement of the micro switch through, for example, a 30 degree angle stroke.
Moreover, a wobblefram can be formed from a relatively flat face by a punch and die at certain elevated temperatures. The basic micro switches utilize a wobblefram element to maintain a hermetic seal and transmit a plunger rotation from outside to a sealed internal mechanism. In particular, the lever in the solid center region is loaded and actuated to transmit motion from outside of the micro switch to the sealed internal mechanism in order to perform the switching function. In a normal process of actuation, the lever and the solid center region can wobble back and forth; hence such a device is referred to as a “wobblefram”.
In the majority of prior art micro switches, a major concern is that normal switching actuation leads to fatigue cracking of the wobblefram below the stated specification of 50,000 cycles (e.g., typically between 25,000 and 50,000 cycles). Some prior art wobblefram designs improve the lifetime up to 100,000 cycles. Such a design, however, affect the operating characteristics of the micro switches due to its flat face. In addition, an accurate model for capturing uncontrolled dimensional variations is difficult to construct, because the operators on the factory floor bend and adjust internal and external mechanisms to obtain the correct switching performance characteristics. Therefore, it is desirable to explore new techniques for improving the fatigue life of a wobblefram, about a factor of 6×, (i.e. at least up to nearly 200,000 cycles), without affecting the operating characteristics of the micro switches.
A need therefore exists for methods for improving fatigue life of a wobblefram, which achieves a drop-in replacement for the original design in the context of micro switch applications. Such an improved method is described in greater detail herein.